Tubing calipering device



May 5, 1953 Fig.|

J. V. FREDD TUBING CALIPERING DEVICE Original Filed June 9, 1949 8 Sheets-Sheet 1 ya; ya.

6m WM y 5, 1953 J. v. FREDD 2,637,117

TUBING CALIPERING DEVICE Original Filed June 9, 1949 8 Sheets-Sheet 2 y 1953 J. v. FREDD 2,637,117

TUBING CALIPERING DEVICE Original Filed June 9, 1949 a snee ts-sheet a Fig.

May 5, 1953 J. v. FREDD TUBING CALIPERING DEVICE 8 Sheets-Sheet 4 Original Filed June 9, 1949 iii/7 I z i 5 I///// rrErrrrEEE May 5, 1953 J. v. FREDD TUBING CALIPERING DEVICE Original Filed June 9, 1949 Fig.l6

8 Sheets-Sheet 5 y 5, 1953 J. v. FREDD 2,637,117

TUBING CALIPERING DEVICE Original Filed June 9, 1949 I 8 Sheets-Sheet '7 vmx I V i i Fig-22 r "f May 5, 1953 J. v. FREDD 2,637,117

TUBING CALIPERING DEVICE Original Filed June 9, 1949 8 Sheets-Sheet 8 Patented May 5, 1953 TUBING CALIPERING DEVICE John V. Fredd, Dallas, Tex., asslgnor to Otis Pressure Control, Inc., Dallas, Tex., a. corporation of Delaware Original application June 9, 1949, Serial No.

97,940. Divided and this application September 12, 1950, Serial No. 184,497

7 Claims.

The present invention relates to a device for simultaneously calipering and recording accurately the internal surface conditions of pipes, tubes and like conduits. The device has special utility in the'determination of variations from the normal of internal surface configurations such as the inner surfaces of extended lengths of connected conduits, particularly oil well tubing.

It is well known that oil and gas Well tubing becomes worn and corroded after periods of use, depending upon the operating conditions to which it is submitted. Many wells produce, in addition to oil and gas, salt water or water having a high acidic content which actively attacks and corrodes the tubing resulting in the formation of pits and depressions on the internal surfaces of the tubing. In addition to corrosion, scoring and wearing of the internal surfaces of the tubing is caused by the passage of well tools through the tubing and by the presence of foreign materials in the fluid flow. The indentations on the tubing walls resulting from the scoring and corrosion are sometimes so severe that the wall thickness of the tubing is reduced to such an extent that it cannot withstand the pressure of fluids flowing therethrough or support its own weight- Consequently, the tubing becomes ruptured or parted, frequently subjecting the casing and surface connections to excessive and dangerous pressures and necessitating its hazardous removal at great cost after the damage has been done. To prevent such failure of the well tubing, it is desirable periodically to determine the condition of the inner walls of the tubing in order that replacements can be made or proper precautions taken to prevent any of the tubing becoming ruptured.

Calipering devices which usually involve the application of electrical circuits, are now available ior measuring variations in the internal surfaces of well tubing. However, devices of this type are not especially adapted for use with well tubing which is under pressure due to the practical difficulties incident to using cables and other electrical equipment which are required to effect the recording.

The present device is entirely mechanica1 in operation and is so constructed that it is readily utilizable with available equipment which is customarily used in auxiliary, well operations, for example, such equipment as is used in tool fishing, well surveying, running and pulling tubing safety valves, chokes, bottom-hole regulators, etc.

It is a principal feature of this invention to provide a calipering device which may be lowered or dropped" as a unit by a suitable wire line into the tubing or a well under pressure and effect a continuous record of the internal surface configuration of the tubing as the device passes upwardly therethrough. After the device is removed from the tubing the continuous record is examined and from this record the extent of the defect and the exact location of the tubing lengths which must be removed and replaced are readily and accurately determined.

This is made possible by the design and arran-ement of the calipering or feeler mechanism. Thi mechanism comprises a plurality of independently operated elements, each of which is actuated in accordance with any pit or depression which it encounters as the calipering unit is passed through the tubing. Upon the actuation of any of the calipering elements, a stylus which is positioned in recording relation to a cylindrical chart will be actuated and, consequently, each independent pit or depression is recorded. By arranging the calipering elements to be independently operable, variations from the normal inner radius of the tubing will be indicated, that is, as a pit or depression is encountered the calipering elements independently enter a pit or depression and a record is effected. The record, however, will show only the deepest pit encountered, since as mentioned before, the stylus is independently actuated by each feeler and of course the principal concern is with the worst corrosive area for a determination of tube removal.

In addition to being independently operable the calipering elements or feelers will operate as a group when a joint or connection between adjacent tubes is encountered. This latter function of the calipering elements is very important in the practical use of this invention, since the record effected for the jointures encountered will all be generally of equal magnitude and will appear at substantially equally spaced points on the recording chart. For example, consider a well tubing string of extreme length, such as from five to ten thousand feet, made up in thirty foot sections and joined together by internal or external collars. As the calipering unit is passed through the tubing and the joints are encountered, the calipering elements acting simultaneously, will be forced inwardly or outwardly as a group, depending on whether the couplings for the tube sections are inside or outside couplings. Each time the calipering elements encounter a coupling of the well tubing the stylus member will be moved longitudinally of the chart subparticular section or sections which are corroded or pitted can be readily determined from the recording chart. It will be understood from the above that the calipering portion of the unit is arranged to provide two complemental functions. An operator of the instrument can caliper .tubing in wells of great depths and also determine, from the recording chart, the exact location of all pits or depressions encountered within the tubing, particularly those which may be considered hazardous to the further operation of the well tubing. it will further be seen that the calipering unit is designed to permit its construction to be varied for calipering different sizes or" well tubing and that it is particularly adapted in its construction and arrangement of cooperating parts to be used with well tubing which is operated under high pressures.

The tube caliperlng device of the present invention differs from known devices in that a stationary cylindrical chart is provided to receive a record during the calipering operation and a V helical record is efiected through the simultaneous rotative and longitudinal movement of the stylus relative to the chart.

The rotative effect of the stylus is brought about through the medium of a drive wheel and two pressure wheels which are maintained in contact with the inner surface of the tubing and tend additionally to center the device therein. Suitable gearing and various other cooperating elements are positioned within a specially designed housing and located between the drive wheel and stylus.

The calipering elements in one useful embodiment are bell crank levers and are located in the housing above the stylus. Each has a lateral arm which extends inwardly toward the axis of the housing and a depending arm which is disposed at' an angle of 90 to the lateral arm. A spring is provided for each calipering element to exert pressure on the lateral arms and to force the depending arms outwardly of the housing to be in operative contact with. the tubing during the calipering operation and, additionally, provision is made to maintain the calipering elements in retracted or non-operating position as the device is initially passed downwardly through the tubing.

A lead screw is provided which is non-rotatable but is urged longitudinally of the housing constantly by a spring in a compartment located above the drive wheel, and urges a bearing surface constantly against the lower surfaces of the lateral arms of the calipering elements. A cooperating spring is positioned above the calipering elements and axially of the housing which forces constantly another bearing surface axially of the housing against the upper surfaces of the caliper lateral arms. The pressure of these springs above and below the lateral arms of the calipering elements provides an arrangement for, centering the caliper in the tubing under all conditions.

In order that no substantial area of the internal surface of tubing which is being calipered be uncalipered or uninspected, a substantial number of the elements are utilized. It has been found, for example, when calipering tubing of Q about inches in enter, that fifteen calipering elemwts are required to caliper the complete inte surface of the tubing. This relatively great nber of calipering elements requires that each be of a particular design in order that they can be carried by and disposed within a housing of sufiiciently small diameter to be passed through such small diameter tubing. The calipering elements preferably terminate at their calipering ends in wedge shaped areas in order to reduce wear and also terminate at their inner ends in wedge shaped areas in order that these ends may be centered and efiectively controlled by the springs heretofore mentioned.

In the drawings:

Figure l is an elevation of the calipering device.

Figure 2 is a partial elevation at right angles to Figure 1 of section shown by lines 2-2.

Fiwe 3 is a vertical section of Figure 2 on lines 3-3:

Figure 4 is a sectional elevation of the release assembly and ieeier fingers.

Figures 5, 6, 7 and a are details of elements in Figure i.

Figures 9 and 10 are cross-sections of Figure 4 on lines 9-Q and l c-11d.

Figure 11 is a sectional elevation of the release, feeler and stylus assemblies.

Figure 12 is an enlarged detail in sectional elevation of the lower half of Figure 11.

Figures 13, i i and 15 are sectional details of Figure 12 on lines i3i3, i i-id and lE-iti.

Figure 16 is a sectional detail of the driving mechanism.

Figure l? is an enlarged detail of the chart member.

Figure 18 is a separate detail of the stylus mechanism.

Figure 19 is a sectional detail of the driving ratchet assembly.

Figure 20 is a cross-section oi Figure 19 on line 23-253.

Figure 21 is an enlarged section of the lower part of Figure 16.

Figures 22. 23 and 2e are a development and sections of the driving gear train.

Figures 25 and 26 are details of the loading top sub A. Adjoining the release assembly B, the

feeler head assembly C is shown divided into two parts which enables adjustment of the feeler mechanism as required under varying conditions. A stylus bushing assembly D is enclosed in the next lower section which is similarly readily disengaged for inspection and adjustment. The next lower section of the housing marked E encloses the chart on which the record of the calipering is marked and is referred to as the chart chamber. Between the chart chamber E and the stylus driving mechanism G, a ratchet assembly section F is inserted to protect the driven stylus mechanism and insure accurate records. At the bottom, plug H closes the end of the instrument housing and afiords a connection for a second calipering device or other instrument. In describing the details of these sections,

the instrument will be considered from the top to the bottom as here outlined, and the same numerals will be used to indicate like elements throughout the drawings.

Reference is made to Figures 1, 2, 3 and 4 forthe details of the release assembly B and the connection between the release and the feeler head assembly C. Through a description of these figures the primary purpose of assembly B, which is to hold the feeler fingers 58 retracted until the survey is to begin, will be clearly understood. The releasing mechanism of the release assembly includes a dog 50 shown projecting from the body of section B in Figure 1. A side view of this section on lines 22 of Figure 1 is given in Figure 2 showing the transverse slot opening 5! in the instrument housing which permits the dog to project outwardly on the opposite side. The cylindrical discs 52-52 retain the dog 50 and the release link 53, connected by a flat curved spring 54, in operating position. Figure 3, which is a cross-section of Figure 2 taken along line 3-3, shows the position of the dog 50, the latching link 53 and the flat curved spring 54 as the instrument is moving upwardly in the tubing string T. The dog 50 is projected outwardly and upwardly ready to engage the joint W of the tubing string T united by collar U. One of the discs 52 has been removed in order to show the relative positions of the elements of the release mechanism.

To release the feeler fingers to operating position, the motion set up by the dog 50 engaging a tubing joint is transmitted by the release link 53 to the head 51 of the release plunger 58 which is partially shown in Figures 2 and 3 but more fully detailed in Figure 4 to which reference is now made. The release link 53 is connected to the release plunger head 51 by pin 59. The end of the head opposite the connection at pin 59 is recessed to receive a set screw 60 and is beveled on surface 6| to clear the dog 50 after it is forced down to the unlatched position by the rotation of discs 5252. Within the release plunger 58 the release rod 62 is fastened by the set screw 50 and extends downwardly to terminate in the head 53 which, in the latching operation, engages notches in the feeler fingers and holds them in a retracted position (as shown in Figure 11) for running the caliper into the tubing string preliminary to the surveying operation. A bushing 64 retains the release plunger 58 slidably aligned in the feeler head 65 and acts as a retaining surface for the centering spring 66. After the feeler fingers are released, the head 63 of the locking piston 62 is lifted and held in position within the centering plunger 61 with which it is in slidable engagement in the bottom section of the feeler head 65. The centering plunger is moved downwardly within the body member by the action of spring 66 into contact with the feeler fingers 68 and urges them outwardly against the wall of the tubing with equal force, thus minimizing the errors which would arise due to the center line of the caliper moving away from the center line of the tubing string.

Continuing with reference to Figure 4 and referring also to Figures 5, 6, 7, 8, 9 and 10, the

feeler head 65, referred to above, and the feeler I head assembly section C of the calipering instrument will be described in detail. Standard machine shop operations have been used to produce an accurate and easily handled assembly locus for the feeler mechanism as shown by the stripped down feeler head in Figure 5. The thread 59 of release assembly B engages a like thread 10 on the feeler head and properly unites these two elements in operating position. The milled slots ll, annular groove I5 and threaded section 90 form the basic structure to receive the feeler fingers which explore the tubing wall. Coupling with the next lower section of the caliper is facilitated by thread 95.

The machined structure of the feeler head just described, is particularly adapted to support the feeler fingers and permit their explorations to be transmitted to a record chart. Consideration of the design and structural advantages of the feeler fingers will readily indicate the cooperation of the elements in this section. Figure 6 shows one of the feeler fingers 68 which'is in the form of a bell crank with an inwardly extending arm 12 and a downwardly extending arm 13 pivoted by the pin ll. These pivoting pins are end ground to abut the adjoining pins as they rest in the annular groove 15 of the feeler head and are consequently positioned securely in circumferential relation. This construction permits the use of a greater number of fingers than could hitherto be used and also makes it possible to easily locate the feeler finger pins radially and axially with extreme accuracy. The feeler fingers of the rigid surface contact type, as distinguished from the well known roller type, are especially designed to'besensitive to pits in tubing which have heretofore been missed. By eliminating the feeler wheels, the required thickness of the fingers is reduced, making a more sensitive feeler and permitting the use of a greater number of them. The contact surface 16 is a tip of hardened steel or suitable alloy, such as carboloy, fitted into the downwardly extending arm. In general, the profile of the contact surface is designed to simulate the action of a small diameter wheel in moving into and out of corrosion pits. The distance from the center of this imaginary wheel to pivoting pin 14 is the same as the distance from pivoting pin 14 to the center of the small radius which forms the contact surface 84 of the inwardly extending arms 12, and the angle formed by the lines connecting each center with the pivoting pin is ninety degrees. This makes the radial motion of the contact surface 16 of exactly the same magnitude as the axial movement of the contact surface 84. As will be noted by reference to the sev eral views showing the feeler fingers in retracted and operating positions, the several beveled edges perform distinct functions. The lower beveled edge 11 is angled to permit the downward movement of the calipering device to proceed freely Without catching in the tubing joints when the per is dropped after initial release.

fingers are extended, which is required if the cali- The upward movement-is likewise freely permitted by the angled edge 18. The edge l9 is cut to lie in the plane of the housing of the instrument when the fingers are in normal contact with the tubing while the edge is flush with the housing when the fingers are retracted by the release mechanism preliminary to the start of a survey. To receive the head 63 of the locking piston 62 when the fingers are latched in the retracted position, a notch 81 is ground in the inwardly extending arm 12. An additional notch 82 on the top of the inwardly extending arm 12 is designed to receive the feeler rods 83 which spring load the individual fingers and extend them to contact with the tubing. By using this feeler rod construction, it is possible to install larger diameter, fiat-rate springs and adenine gain mechanical advantage when the reeler fingers approach top dead center, thus compen= eating for the spring load increase under com pression through the piston and connecting rod action. However, to keep the reeler head cen= tered in the tubing bore and maintain maximum accuracy. it is essential that the leeler point load increase slightly at a uniform rate as the reeler fingers move inwardly. Optimum load on the contact surface oi the feeler fingers is thus achieved regardless of radial position. A rounded edge 85 is the contact through which the movement of the fingers is transmitted to the stylus which will be discussed later in detail.

Referring again to Figure 5, the annular groove is in the feeler head is machined to receive the pivoting pins l which abut each other circumferentially as explained above. A retainer ring he, detailed in Figure 7, with slots 86, and

counter-bored as at 5?, caps the feeler fingers and the pivoting pins and holds them securely in place. To hold the retainer ring in place and facilitate assembly of this element of the instrument. a nut 88, Figure 8, is internally threaded at to engage like threads Qt on the feeler head. Enclosing the leeler head assembly is a sleeve 92 which fits into shoulder ti on the nut 88 as the lower support and is received in a like shoulder 9d of the release assembly section B to support the upper end. Within the enclosed space defined by this sleeve and the ieeler head are housed the :feeler finger activating mechanism and means to adjust their operating force.

Returning to Figure 4 wherein these elements are shown in enlarged detail, immediately below the release assembly section Band secured thereby is a spacer washer 98 which may be varied in thickness to extend the spacing between the release assembly section and the ieeler head assembly mechanism to vary the feelerspring compression and feeler point loading, either with or without a change in thelength oi the spacer sleeve. A guide ring til, retained in radial position by a Woodrufi key K, is mounted to receive the spring guides 98 and retain the individual ieeler finger operating springs 33. These guides serve as the only means of keeping the springs from interfering with each other as they are located in an annular space with only small clearance between them. On the lower ends of the spring guides 9d. the heads 8%, aligned radially by the sleeve 92, abut the lower ends of the springs 93, cause the guides to move downward against the feeler rods 83 and thus transmit the thrust to the feeler fingers 88 as shown. This construction allows the greatest circumference of the device to be used for mounting of the spring guides 98 with the maximum perimeter spacing of the springs. In turn, this permits the use of springs of larger size together with a greater number of feeler arms. The feeler rods 83 are rounded both. at the top and bottom to seat in sockets I00 in the heads 90' of the spring guides and in the notches 82 in the inwardly extending arms 12 or the feeler fingers 58.

Figures 9 and 10 complete the detailed description of the feeler head assembly and are cross-sections taken on Figure 4 to clearly show the arrangement and location of the feeler arms and guides. The upper section shown by Figure 9 indicates the circumferential distribution of the guides 98 and the springs 93 about the Iecler head 65. The centrally located release rod 52 is also shown properly positioned within the :Eeeler head. Figure 10 is a cross-section taken below section 9 and demonstrates the po sition of the ieeler fingers 68 in both the normal and extended operating positions as in entering a pit P. This latter cross-smtion is taken just above the pivoting pins l6 or the ieeler arms t8 and shows all intersected parts in sectional symbol.

The nest details of the caliper to be considered are the stylus bushing assembly D and the chart chamber section E which closely cooperate, both internally and externally, and will be described together. Reference is made to Figure l tor the assembly and external appearance and to Fig urea 11, 12, 13, it, 15, i6, i7, and 18 for a de-= scription of the mternal elements and their co= operation. The stylus bushing assembly D threadly engages threads on the lower end oi the ieeler head 6?; and is thereby properly po sitioned in the assembled instrument. it will be noted in Figure i that all threaded members are provided with shallow holes to receive span ner wrenches for making and breaking the joints as required for complete assembly and disassembly. Figure 11 gives the above threaded joint in detail and further shows the slip joint lei oi the chart chamber closure Hill where it joins the stylus bushing assembly. Chamber screws IE2, made from hardened, fine-thread socket set screws with heads tapered down to fit tightly into holes in the chart chamber closure, complete this connection and prevent disengagement during operation. A pressure relief hole ltd is drilled through the chart chamber closure ltd to permit uninterrupted operation of the chart chamber elements during the survey which nor mally takes place under pressure conditions. Reference toFigure 16 shows the lower end oi the chart chamber closure to be a duplication of the upper end just described so that in assembly either end may be placed upward and no mistake is possible.

The sections of the calipering device now under discussion are seen more clearly in Figure 12. Starting at the top of this figure with the feeler fingers 68, which have been described above in detail, the rounded edge 86 of the under side of the inwardly extending arms it are normally in contact with the head end I05 of the stylus rod tut. In this view one of the feeler arms has moved outwardly to a greater degree than the other arm as on entering a pit or depression and is pressing the stylus rod downwardly. A slot i0! is let into the stylus rod I06 to pass the p 108, mounted in the adjustable member :09 of the stylus bushing,which prevents rotation of the stylus rod yet permits the desired axial movement set up by the feeler fingers. A stop E E0 abuts the end of the adjustable bushing member to prevent the upper edge of the stylus rod slot from striking and shearing the pin M8. As designed, the stop also prevents the pin from slipping out, thus preserving itsprimary function, namely, to prevent rotation of the stylus rod. Another slot III in the lower end of the rod I06, cut to receive the milled end of the stylus lead screw H4, permits ready disassembly without disturbing the fixed ratchet H2 of the stop clutch H3 and further prevents the stylus lead screw from rotating. The maximum dimeter to which the feeler arms may be extended is adjusted axially within the device by the adjustable member I09 which threadedly engages the stylus bushing D, as shown. The lockassau t,

ing nut H preserves this adjustment once it is made. The set screw tit retains the ratchet I M in fixed position.

Having described the stylus bushing assembly D down to the stop clutch, it is logical from the joints and physical construction to consider the elements immediately below this point as parts of the chart chamber section E. Starting with the internal construction, the stylus rotating mechanism extends downwardly from the movable ratchet H? of the stop clutch II3 of Figure 12 to the driven ratchet N8 of the drivin clutch H9 in Figure 16. The assembled detail of this part of the mechanism is illustrated in Fi ure 17 and is separately shown in Figure 18. Sectional views, necessary to a complete understanding, are given in Figures 13, 14 and 15. With reference to Figure 1'7, the stop clutch II3 includes a fixed ratchet H2 and a movable ratchet II'I. Attached to the movable ratchet are the drive rails I20 which extend downwardly to engage the driven ratchet II8 of the driving clutch II9. These driving rails are suitably fastened on both ends to the ratchets as shown in this figure. The non-rotatable stylus lead screw H4 is positioned through both clutches and is supported by the conical bearing I2I. A stylus I22 is housed in the stylus holder I23 designed as a travelling nut and slotted at l24-I24, as shown in Figure 15, to receive the drive rails I20 which rotate it about the lead screw I I4. Forming a part of the travelling nut i23, a threaded extension I25 extends the threaded contact area over an added length of the lead screw for better operation and control. The stylus lead screw I I4 is centrally positioned in this figure which also discloses the relation of the stylus holder parts together with the stylus spring I20 used to urge the stylus into contact with the surface of the chart I27. A single coil spring is used to load the stylus point more uniformly than could be done with a small diameter spring. Moving upward on Figure 12 of which Figure 15 is a crosssection, another section Figure 14 shows the movable ratchet II'I of the stop clutch II3 with the lead screw II4 passing through the center. The assembly of this clutch element and the drive rails I20, considered with the elevation of the stylus driving mechanism assembly as shown in Figure 18, clearly illustrates the arrangement of these elements. A section of the upper chart retainer I28, slotted at I29 to permit contraction and expansion to position and fasten the chart I 21 in place, is included in the sectional view of Figure 14.

The circumferential dimension of the chart retainer I28 is such that, when in place as shown in Figure 14, the slot I29 is of sufficient width to cooperate with pressure relief hole I03 (see Figure 12) in chart chamber closure I04 to permit pressure equalization throughout the instrument duing operation under pressure conditions. When the caliper is assembled care must be taken to locate slot I29 opposite hole I03 in order to permit the aforesaid pressure equalization.

Enclosed within this section E are the chart [21, chart retainer I28 and a similar retainer I3I in the lower part of the chart chamber and are clearly shown in details of Figure 17. The upper and lower chart retainers are beveled on the edge toward the chart with a shoulder at points I32 and I33 respectively to Wedge the chart in place and prevent any movement of the chart surface during the calipering operation. A disengaging device comprising a sleeve I34 slidably encircles the stylus lead screw near its lower end and freely fits within the driven ratchet of the driving clutch H9. The internal and external surfaces of the sleeve being smooth, no intended motion of rotation or retention are transmitted to it by the elements adjacent thereto. To keep the disengaging device from falling out of the driving clutch when the caliper is disassembled, a retaining ring I35 is fastened on the upper end. The length of this device is suflicient to extend through the upper ratchet of the clutch II 9 and into the lower ratchet MI in order to provide for transmitting pressure to the lower ratchet at the end of the stylus travel as will be fully discussed in describing the operation of the caliper.

At the upper end of the ratchet spring assembly F, adjoining the lower end of the chart chamber;

closure E, are a slip joint I 36, chamber screws I31, and a pressure relief hole I38; all similar to the structure and like elements described for Figure 11 and, as pointed out there, intentionally so constructed to prevent mistakes in assembly. The O-ring I39 is set into a groove I30 to retain the lubricant with which the chart chamber is filled.

Continuing downward in the examination of the details of the caliper, the ratchet assembly F is the next section to be detailed and is locat ed externally in Figure 1 and internally in Figure 16which sectionalizes the elements and indicates their operating relation. For the description of these elements general reference is made to these two figures, 1 and 16, and special reference is made to Figure 19. In this latter figure, and continuing downward from the slip joint I36 by which the chart chamber section E and the ratchet spring assembly F are joined, the housing I40 is designed to receive the elements which transmit rotary motion to the stylus. The driving ratchet I4I of the driving clutch H9 comprises a reduced tubular extension I42 which terminates at the upper end with the ratchet teeth and extends axially through the bore I43 in the slip joint end of the housing I 40. Equispaced holes I44--I44I44 are drilled through this en o t e ous n as shown in section in Figure20, to permit the transfer of lubricant between the'chart chamber section and ratchet spring assembly. The lower end of the driving ratchet MI is an enlarged and bored section I45 telescoping with the driving member I46. In the walls of the section I45, longitudinal slots I41 are cut to slide over and engage pins I48 on the driving member I46 insuring rotational move ment of the driving ratchet. A ratchet spring I49 envelopes the driving membertw and urges the driving ratchet I 41' upward tofengage the ratchet teeth with the driven ratchet II8. Enclosed within the member I48, the stylus lift spring I50 exerts an upward pressure on the stylus lead screw plunger I5I which supports the stylus lead screw H4 in the conical bearing I2I. The section of the plunger adjacent spring I50 contains the upper section of a fiuid'fiow control I52 which, cooperating with the adjustable screw stop I53 mounted in the stand I54, cushions the downward stroke of the lead screw I I 4, by decreasing the flow path of lubricant filling this part of the device. The pin I55, placed diametrically across the flow control I52, limits the downward movement of the lead screw after the speed of travel has been decreased by the upward movement of the lubricant around the screw I53 and through the control. The adjust- 'threads of the section able screw stop is adjusted to halt the downward travel of the lead screw only after the feeler arms have been permitted to reach their maximum outward movement. The base I58 of the driving member I46 is flanged to support the spring I49 and is machined down to a shaft I51 with a conical bearing I63. At the lower end of the housing I40 the thread I58 connects the ratchet spring assembly section F to the drive mechanism section G.

Details of the flanged base I56 of the driving member I46 and the bearing plate I58, drilled at I60 to permit lubricant to pass downward, are repeated in Figure 21 which shows the details of the driving mechanism in section G. The upper threaded end I6I, adapted to engage the above, is counterbored to form the gear chamber I62. Supported by the bearing I63, the shaft I51 of the driving member I46 is fitted with the gear I64 which forms part of a gear train fully developed in Figures 22 and 23. By reference to these figures as well as Figure 21 now under discussion, it will be understood how the rotary motion of shaft I85, transmitted by gear I66 which is keyed thereon, is passed through gear I61 to shaft I68 and thence through gear I68 to gear I64 on the shaft of the driving member. A fuller understanding of the origin of the rotary motion, which is imparted to the shaft I65 and sets the gears in motion, will be understood by referring to Figure 24 in conjunction with Figure 21. The drive wheel I10, which is rotated by contact with the inner wall of the tubing string as the calipering instrument is raised or lowered, is rotatably mounted on a fixed shaft I1I. Interposed between the rotatable drive wheel and the solid body portion I13 of the drive mechanism section G, through which the lateral slots I14 and I are machined to mount the worm gear and the drive wheel respectively, the brass washer I12 is mounted to reduce wear. The worm gear I16 is secured to the drive wheel in the slot I14 and meshes with the worm wheel I11 which is keyed to the bottom of the shaft I65. A sleeve I18. split on the line of the edge of the drive wheel 810 to permit its free rotation, is fitted over the slotted portion of the solid body I 13 to close these assembly openings. In the lower part of the drive mechanism body I13, intersecting slots I18-I19 are milled to receive the two loadin wheels I80-I80 as shown in. Figures 21 and 25. These wheels are beveled on the contact periphcries to conform to the arc of the inner wall of the tubing string and thus insure maximum contact area and constant pressure. Each of the loading wheels I80-I80 is rotatably journaled in a loading arm of the design shown in Figure 26, and each loading arm is, in turn, pivotally mounted within the intersecting slots. As will. be seen in Figure 26, each loading arm I8I is slotted-at I82 providing a space between upstanding walls I83I83 which receive a loading wheel I80. The loading wheel is rotatably mounted on a shaft I84 which extends through the holes I65 of the loading arm. Retaining each loading arm in place within the slots I18-I18, a pivot pin I86 passes through the hole I81 in the loading arm and the holes I88-I88 drilled in the body I13. Thev bottom of each loading arm is cut to provide shoulders I89 and I80, the former spring pressed upwardly by piston I8I which fits into the drilled hole I82 in the bottom of the drive mechanism body I13 and the latter acting as a check against unrestricted outward movement of the loading arm. The

, l2 bore I83 within the-piston contains a spring I84 which is the activator for the piston and is maintained under compression by the plug I85 threadedly engaging the lower end of the body member I13.

Returning to Figure 16 to complete the description, the plug H is shown as centrally drilled and tapped at I86 to receive additional tools or another calipering instrument if it is desired to use these devices in tandem. A hole I81 may be drilled through the plug I95 to admit well fluids to the piston chamber if desired.

It is believed the detailed description above will be sufliciently understandable to those verserl in the art to visualize the operation of the de-- vice. However, as the cooperation of the elementsabove defined gives a long sought for result with a high degree of accuracy and exceptional performance characteristics were noted under test, an example of the calipering of a tubing string under pressure conditions will be related. This instrument is designed to operate under high pressures if necessary without killing the well, and in the presence of any well fluids or gases, including salt water and drilling muds. The elements of the caliper, for use under such general conditions, are made to be highly corrosion resistant, either by making the parts of stainless steel or Monel metal, or by cadmium or chromium plating hardened tool steel. It will be further understood that special equipment for introducing the calipering device into wells under pressure is necessary. Among the items used for such equipment may be named hoisting and reelmg machines, depth gauges, high pressure stufllng boxes, pressure chambers known to the trade as lubricators, gate valves and the like, which are merely referred to here as they form no part of the claimed invention.

Preparatory to using the calipering instrument for a tubing string survey, it is possible to separate it into its component parts as shown in Figure 1 and make a thorough check of the mechanism for undue wear and operability. This is a feature of the device and requires very little time and a minimum of standard tools. All parts of the apparatus are readily accessible and easily adJusted or replaced. The usual preparation for a calipering run is limited to separating the instrument at the slip joint "II which unites the stylus bushing assembly D with the chart chamber E and lifting the lead screw and stylus operating mechanism (Figure 18) from the chart chamber. The used chart, if any, is removed and a new chart, which may be of any preferred material but in this example is made of sheet steel shim stock properly treated on the tracing face to be marked by the st lus I22,

in the chart chamber and him secure ly b y igg per retainer I28 and the lower retainer I3I, as shown in Figure 12. These retainers position the chart axially and hold it flat against the chamber wall, preventing any movement of the chart. To place the stylus in a position ready for operation, the stylus holder is rotated until it is at the top of the lead screw and the upper edge of the chart, also illustrated in Figure 12, and the stylus operating mechanism is put back in the chart chamber being sure the lead screw and driving clutch are properly positioned. Lubricating 011 is then poured into the chart chamber until the ratchet assembly and chamber are filled to keep well fluids at high pressures from affecting the internal mechanisms, and then the device is reassembled by connecting the stylus joint positioned there to prevent leakage.

13 bushing to the chart chamber at the joint previously separated. This slip joint, which is typical of similar connections used in this instrument, is made rigid by using chamber screws M2 which are tapered, socket set-screws. On disassembly they are rotated into the stylus bushing body and on reassembly they are backed out after the joint is united tcfit firmly in holes drilled to receive them in the chart chamber closure I04 (Figure 11). As the full well pressures are admitted to all parts of the caliper mechanism, including the recording stylus and chart, and equalized throughout by means of the lubricant filling these spaces, packing glands and gaskets with their inherent frictional drag are eliminated. The result of the equalization and balancing of the well pressures is thatthe stylus follows the smallest variation of each feeler arm as they explore the inner wall of the tubing string. The lubricating oil is retained within the caliper by the synthetic rubber O-ring gasket set in the groove at the lower chart chan ilbler e feeler fingers are then pressed into the retracted position and held there while the head of the release rod 63 is lowered into locking engagement with the notches provided in the feeler fingers by rotating the cylindrical discs 52 which also places the dog 50 in the locked position. The

feeler fingers being urged outwardly by the pistonlike action of the feeler rods 83, as shown in Figure 12, press against the release rod head 63 and remain locked until the release rod is lifted. The caliper is now ready to survey the tubing string of our example.

By arranging the pressure retaining equipment enumerated above, and properly mounting it on the tubing string at the top of the well, the caliper is introduced into the tubing string on a wire line without pressure loss. The caliper is then lowered to the desired depth, the feeler fingers remaining in the retracted position, as described above, during the entire descent. The dog 50, projecting outwardly of the release assembly body and upwardly as shown in Figure 1, is held in light engagement with the wall of the tubing by the action of spring 54 and has sufficient movement to pass freely downward without disturbing the release mechanism. It is retained in this locked position by the load of the feeler fingers pressing against the head of the release rod. On reaching the desired depth, upward movement of the instrument engages the dog 50 in the first tubing joint above the stopping point and causes the release assembly to function, starting as shown in Figure 3 and ending as in Figure 4, lifting the release rod 62 from looking engagement with the notches 8| in feeler fingers 68, permitting them to spring outwardly to contact the tubing walls and begin the calipering operation. The pair of discs 5252 having rotated to lift the release rod, drop the dog downward to lie on the beveled head of the release plunger where the fiat release spring 54, having traveled overcenter, is designed to keep the dog confined within the release assembly body. At all times, the centering plunger 61 is urged downwardly by the compressed centering spring 66, restrained in upward movement by the bushing 64 above, to constantly engage the upper edge of the inwardly extending arms 12 of the feeler fingers 68. The constancy of this action by the plunger is illustrated in Figures 4 and 12 where it will be noted that the only time this is not true is when the individual feeler fingers separately 14 follow pits P. This equal pressure on all the feeler fingers, under normal conditions and on the greater number where pits are encountered, centers the caliper within the tubing string and minimizes errors in the charted record which would otherwise arise.

In addition to the uniform spring pressure of the centering plunger on the feeler fingers, each finger is separately actuated outwardly by the feeler rods 83 which transmit the pressure of the spring guides 98 to each of the fingers separately. The outward movement of each individual finger is limited only by the tubing wall. The caliper is adjusted so the extreme diameter reached by the fingers is the same as the inside diameter of the tubing couplings or collars U. This setting is large enough to indicate complete penetration of the tubing by corrosion and serves as a reference in making an accurate interpretation of the actual depth of corrosion as indicated by the chart. Also, this setting is small enough to permit easy entry of the caliper into the surface connections cr me well and to travel downward through the tubing couplings if the ieeler arms are not inth'e retracted or locked position, as required in repeating surveys over limited tubing lengths. The ideal feeler finger loading is the minimum loading attainable which will minimize the wear on the feeler finger contact surface 16 and possible damage and yet produce an accurate chart if only one feeler finger moves out to its maximum travel. An individual feeler operating spring 93 should be strong enough to move its feeler finger firmly out to its limit of travel while at the same time depressing the stylus lift spring (Figure 16). In turn the stylus lift spring must be of sufficient strength to support the lead screw H4 and stylus holder I23 and keep the head of the stylus rod I05 in continuous contact with the feeler fingers even when the feeler fingers are moving into and out of corrosion pits and tubing collars at fast calipering speeds. The feeler spring compression and consequent feeler finger loading can be adjusted by changing the thickness of the spacer washer 96 and the length of the spacer sleeve 92 or either.

During the downward movement of the caliper in the tubing string, the loading wheels -180 and the drive wheel l 10, Figure 16, are in operating contact with the tubing wall and rotating at a speed commensurate with the rate of movement downward. The direction of rotation of the drive wheel is clockwise when viewed as in Figure 16 and is transmitted through the worm and Worm wheel to the gear train and thence to the shaft i5? which rotates the driving memher 146 and through it the driving ratchet Ml. Centering of the caliper within the tubing string is facilitated by using two loading wheels and pressing these outward to contact the tubing wall by a single spring and plunger acting as a unit on both wheels equally. The driving clutch H9 is'designed to cooperate with the stop clutch H3 (Figure 11) so as to hold the stylus rotating mechanism motionless as the caliper moves downward. Consequently, no trace is made on the chart at this time. As the caliper is moved upward and the release operates, freeing the feeler fingers, the rotary motion of the drive and loading wheels is reversed. The clutches reverse their operation also, the driving clutch ratchets engaging and the stop clutch releasing the ratchets. A rotary motion is thus imparted to the stylus holder by the drive rails I20, Figure 17,

aasmrr 1 and the stylus Scribes the record on the chart,

moving from the top of the chart downward. As

the lead screw is fixed against rotation, the

stylus I22 scribes a helix in descending along the lead screw. thread. ".lhe scribed helix has the same pitch as the lead screw. withthe result that the chart shows a series of parallel lines.

equally spaced apart which aids in visually translating the survey. The horizontal scale of the chart is selected to provide maximum footage per chart while retaining clarity and to distribute tubing joint interruptions horizontally, and may be varied by changing the gears. In

having the stylus more over the fixed chart, I

downwardly on the stylus rod I06. It will be' noted that should two or more feeler fingers move outwardlyat the same time, the effect of that which moves out the greatest distance is alone transmitted to the stylus rod. This reveals the locus and measurement of the greatest defeet and is therefore a measure of the true damaged condition. The sum of the depths of the pits, depressions and joints, is never measured by this device. As the stylus rod is moved downward, this motion is transmitted to the nonrotatable lead screw with which it is in contact, Figure 11, and interrupts the helix which the stylus is scribing on the chart. The design of the feeler fingers detailed above causes the stylus to move away from the basic helical path the same amount as the feeler arms move outwardly. The resulting log, when the chart is removed from the caliper and spread out fiat, is a series of parallel lines which show at true scale the maximum outward feeler movement at any instant during a calipering passage. The spacing of the lines, determined by the pitch of the lead screw, permits visual examination of the survey and exact measurement of the corrosion pits. For example, if the pitch of the lead screw were .050 inch, which is threads to the inch, and the trace of a pit moves up three lines, the pit would be .150 inch deep. Tubing joints show clearly as a series of practically regular interruptions for standard length tubing and are readily identified for any length tubing. The chart lines will vary fromalmost straight to very jagged, depending on the severity or the corrosion. The leadscrew, which receives'the axial motion from the stylus rod, is supported by the plunger I5I, as shown in Figure 1'7. A fiuid flow control I52 is housed in the lower part of the plunger which, operating in the lubricant filling this part of the .device and cooperating with the adjustable screw stop I53, restricts the travel of the lead screw to the desired limit and produces a clearer chart record.

A particular advantage of the disclosed device resides in the ability to recaliper a specific length of tubing without removing the device from the string for re-setting. Within the limits of the chart space, readings may be repeated on a particular section of tubing as desired. It has been seen above that the calipering operation is per-- the string and that when moving downwardly the clutch arrangement is designed to prevent the rotation of the stylus holder. Consequently, a length of tubing may be surveyed by the upward movement of the caliper and resurveyed, until the chart is exhausted, by dropping it down to the point of beginning and again surveying by moving it upward. The release mechanism, having once been unlatched, is not set again but presents no difficulty as the dog is dropped down and readily clears the tubing joints. The feeler fingers also clear the obstructions in the tubing string due to the several beveled surfaces which have been fully described.

hould the instrument be operated beyond the chart limits, however, the record already obtained is preserved unmarred by the operation of the disengaging device I34, shown in detail in Figure 19. All recording action on the chart requires that the stylus rotate and move downwardly on the lead screw which is secured against rotation, but move axially in response to the feeler finger action, as described. Consequently, the survey will ultimately move the stylus holder to the bottom of the chart regardless of whether the run is continuous or repetitious as the clutch arrangement prevents the upward movement of the stylus on the. lead screw even though the drive wheel is responsive to both upward and downward movement. Figure 17 shows the disengaging device I34 in enlarged detail and positions it in cooperating relation with the elements of the device which activate it and upon which it operates. The rotary motion of the drive rails I20 moves the stylus holder I 23 downward on the lead screw H4 during the scribing operation until the bottom of the chart I2] is reached. At this point, the bottom of the stylus holder I23 engages the top of the disengaging device I34. Continued rotation moves the stylus holder further down on the lead screw and presses with increasing pressure on the disengaging device until it forces the driving ratchet Ill away from contact withthe driven ratchet H8. The driving mechanism is then free to rotate without transmitting motion to the stylus driving mechanism from which it has been disengaged. The downward thrust of the stylus holder is transmitted to the lead screw with which it is threadedly engaged and exerts an equal upward thrust through the lead screw to the stylus rod I06, evident from an inspection of Figure 11, and, in turn, exerts an upward force on the feeler fingers causing them to retract sufficiently to withdrawv from the tubing wall and facilitateremovalfrorn the string without unnecessary wear.

The surface operating crew keeps a running tally of the number of feet of tubing through which the survey is made by upward movement of the caliper. The fixed measurements of the chart length and lead screw pitch being known, the number of feet of tubing which can be calipered on one chart is readily determined. The survey having been made, the caliper is withdrawn from the tubing string in reverse operation to that described for starting the operation. The chart is released from the chart chamber and spread for study. Photostats are readily made from the chart, and enlarged if desired, for extensive interpretation and inclusion in survey reports.

The example selected for disclosing the operation of the caliper considered a well under pres sure in which the tubing string was the object of formed only as the instrument moves upward in the survey. This is not the limit of the operational possibilities of this device, and is not so intended. The calipering instrument, as here disclosed, is flexible in application and may readily be used to survey any conduit, pipe or tube in any position and under conditions ranging from atmospheric to very high pressures. Neither is the size of the instrument a controlling factor, but may be increased or decreased to meet specific conditions and will operate with equal facility and accuracy. It is, therefore, the intention of the inventor to include within the scope of this disclosure all devices falling within the spirit of the invention, as well as the letter thereof, limited only by the appended claims.

The feeler arrangement and mechanism for latching and releasing the feelers is not herein claimed as that constitutes subject matter of my co-pending application, Serial No. 97,940, filed June 9, 1949, of which the present application is a division.

I claim:

1. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering means mounted for lateral movement between said housing and the tube wall being calipered, thecombination of recording means including a cylmdrical recorder member fixed against rotation and a stylus member positioned in scribing relation thereto, operating means for said stylus member including a lead screw fixed against rotation and a drive rail for simultaneously rotating and longitudinally moving said stylus member relative to said cylindrical recorder member, driving and transmission means for said operating means, and means for efiecting limited relative reciprocal movement between said recorder and stylus members responsive to movement of said calipering means.

2. A device according to claim 1 wherein the operating means comprise a uni-directional driving clutch, a second uni-directional clutch for preventing rotation of said stylus member when the device is passaged in a non-calipering direction, and means for disengaging the driving clutch as the stylus member approaches the end of its longitudinal travel.

3. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering means mounted for lateral movement between said housing and the tube wall being calipered, the improvement which comprises a fixed cylindrical recorder member mounted longitudinally within the housing, a lead screw positioned co-axially within said recorder member and fixed against rotation, said lead screw being arranged for reciprocal longitudinal movement in response to lateral movement of said calipering means, a stylus member mounted on said lead screw for scribing engagement with said recorder member, a rotary driv rail engaging said stylus member, clutch means at one end of the drive rail, reversed clutch means at the other end of the driv rail, driving means carried by the housing for frictional contact with the tube wall during passage of the device through the tubing, and transmission means between said driving means and one of said clutch means, whereby said stylus member is prevented from rotating when the device is passaged through the tubing in one direction but is caused to rotate and move longitudinally along 18 the lead screw when the device is passaged in the opposite direction.

4. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering means mounted for lateral movement between said housing and the tube wall being calipered, the improvement which comprises a fixed cylindrical recorder member mounted longitudinally within the housing. a lead screw positioned longitudinally within said recorder member and fixed against rotation, said lead screw being arranged for reciprocal longitudinal movement in response to lateral movement or said calipering means, a stylus member mounted on said lead screw for scribing engagement with said recorder member, a rotary drive rail engaging said stylus member, driving means carried by the housing for frictional contact with the tube wall during passage of the device through the tubing, and transmission means between said driving means and said drive rail.

5. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering means mounted for lateral movement between said housing and the tube wall being calipered, the improvement which comprises a lead screw positioned longitudinally within said housing and fixed against rotation, a cylindrical recorder member fixed against rotation and positioned around said lead screw, a stylus member mounted on said lead screw in scribing engagement with said recorder member, means for meeting limited relative reciprocal longitudinal movement be tween said recorder and stylus members responsive to movement of said calipering means, a rotary drive rail engaging saidstylus member, driving means carried by the housing, and transmission means between said driving means and said drive rail.

6. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering means mounted for lateral movement between said housing and the tube wall being calipered, the improvement which comprises a lead screw positioned longitudinally within said housing and fixed against rotation, a cylindrical recorder member fixed against rotation and positioned around said lead screw, a stylus member mounted on said lead screw in scribing engagement with said recorder member, means for effecting lim ited relative reciprocal longitudinal movement between said recorder and stylus members responsive to movement of said calipering means, a rotary drive rail engaging said stylus member.

- clutch means at one end of said drive rail, re-

versed clutch means at the other end of the drive rail, driving means carried by the housing, and transmission means between said driving means and on or said clutch means.

7. In an internal tube wall calipering and recording device adapted to be passaged through an extended length of tubing and comprising an elongated housing carrying calipering 'means mounted for lateral movement between said housing and the tube wall being calipered, the improvement which comprises a fixed cylindrical recorder member mounted longitudinally within the housing, a lead screw positioned longitudinally within said recorder member and fixed 59 against rotation, said lead screw being arranged for reciprocal longitudinal movement in response to lateral movement of said calipering means, a stylus member mounted on said lead screw for scribing engagement with said recorder member, a rotary driv rail engaging said stylus member, driving means carried by the housing for trictional contact with the tube wall, transmission means, including a driving clutch, between said driving means and one end of said drive rail, a reversed holding clutch adjacent the other end of said drive rail, whereby rotational movement of the stylus member is prevented when-the device is passaged through the tubing in a noncalipering direction but is eflected during a cal- 15 ipering passage in the opposite direction. and

20 disengaging means positioned for abutment with said stylus member as the latter approaches the end of its recording travel and thereby operative to disengage said driving clutch and prevent rota.-

5 tion of the drive rail.

JOHN V. FREDD.

References Cited in the file of this patent UNITED STATES PATENTS 10 Number Name Date 1,754,503 Dwelle Apr. 15, 1930 1,867,176 Rieckmann July 12, 1932 2,518,663 Chaney et a1 Aug. 15, 1950 2,544,609 McMahan Mar. 6, 1951 2,567,548 Chaney et al Sept. 11, 1951 

